Naturally decomposing disposable tableware and manufacturing thereof

ABSTRACT

Disclosed is disposable tableware which is completely degradable under environmental conditions without environmental contamination. The disposable tableware is prepared using environmentally friendly, completely degradable materials without additional chemical additives while maintaining the shape and function of general disposable tableware so that it is completely degraded under environmental conditions, thus not causing environmental contamination and problems associated with waste disposal such as separation from other wastes. Also, the present invention discloses a method of manufacturing such disposable tableware. The disposable tableware is prepared by compression-molding a composition including 1–30 wt % of crop residues, 1–30 wt % of corn flour, 1–10 wt % of paper mulberry bark, 1–10 wt % of a moss and 30–96 wt % of a grain flour mixture as the remaining part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage entry of International ApplicationNumber PCT/KR2004/001820, filed Jul. 22, 2004. The disclosure of theprior application is hereby incorporated herein in its entirety byreference.

TECHNICAL FIELD

The present invention relates, in general, to disposable tableware whichis completely degradable under environmental conditions withoutenvironmental contamination, and a method of manufacturing the same.More particularly, the present invention relates to disposable tablewarethat does not contain any synthetic additive and thus is completelydegradable in the natural environment and is suitable for compost, and amethod of manufacturing such disposable tableware.

BACKGROUND ART

As human life and culture become diverse and complicated with industrialdevelopment, various types of disposable tableware have been produced tosave time, including spoons, cups, dishes, lunch baskets and otherdisposable living necessities.

Currently used disposable tableware is mostly made using syntheticresins (e.g., polystyrene), pulp, and the like.

However, disposable products manufactured using synthetic resins containingredients harmful to humans. Also, they are major causes ofenvironmental contamination due to problems associated with wastedisposal by their increased use, and thus have a limitation in use.

In addition, paper products manufactured using pulp have the followingproblems: they are not economical because most raw materials includingpulp are imported; forests have been damaged in the production of theraw material, pulp, resulting in environmental disruption; and pulps aretreated with synthetic additives during processing, thus causingenvironmental contamination. These problems may be partially solved byrecycling used pulp. However, enormous energy is required for therecycling of pulp, and various additives are used in a recyclingprocess, thereby bringing about secondary environmental contamination.Also, pulp is typically waterproof-coated with vinyl to solve itsstructural problems. However, these coated products have been alsorestricted in use by various environmental regulations because theycause environmental contamination.

Thus, in restaurants and other places, this disposable tableware isinconvenient to use because they should be recovered separately fromother general wastes after being used.

This restriction in the use of disposable tableware is because mostconventional disposable tableware is not environmentally degraded andthus cause contamination of the soil when buried under the ground orproduce environmental contaminants such as dioxin when burned.

To solve these problems, efforts were made to develop environmentallydegradable disposable tableware. However, the resulting tableware isproblematic in terms of requiring high production cost and not beingpractical.

Environmentally degradable disposable tableware will be described indetail, as follows.

In recent studies, attempts were made to replace polystyrene withnatural polymeric materials obtained from starch from grains or wheatflour, crop residues, and the like.

Grain flours may be used as described in Korean Pat. Publication No.96-0006565 which discloses a method comprising mixing and kneading wheatflour, starch, baking powder and salts, molding the resulting dough, andfreezing and coating the molded dough, or in Korean Pat. Laid-openPublication No. 99-0047173 which discloses a method comprising mixingand kneading main materials, starch of grains and wheat flour, withauxiliary materials including sugars, aromatics and yeasts in purifiedwater at a proper temperature, maturating the resulting dough, extrudingthe maturated dough, and molding, freezing and drying the extrudeddough. In addition, the grain crop residues may be used according to amethod as described in Korean Pat. Application No. 99-0055567, whichcomprises mixing pulverized hulls from rice, barley, German millet,Indian millet, and the like, starch and water, and molding and coatingthe resulting dough, or another method as described in Korean Pat.Application No. 99-0037967, which comprises mixing vegetable particlesused as a major material, prepared by pulverizing corn stalks or variousseed coats, with an edible glue, and compressing the mixture with amolding agent.

However, the resulting products have limited applications because theyare heavy, easily destroyed, and contracted by outdoor temperature.

To solve these problems, natural polymers have been used as mainmaterials inevitably in combination with non-degradable additives. Thus,the resulting products are also problematic with regard to degradationand production cost, thus making their practical use difficult.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide disposable tableware with no risk ofenvironmental contamination, which is prepared using environmentallyfriendly, completely degradable materials without additional chemicaladditives while maintaining the shape and function of general disposabletableware so that it is completely degraded under environmentalconditions, thus not causing environmental contamination and problemsassociated with waste disposal such as separation from other wastes, anda method of manufacturing such disposable tableware.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 show disposable tableware molded according to embodimentsof the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

FIGS. 1 to 3 show disposable tableware molded according to embodimentsof the present invention. Disposable tableware with no risk ofenvironmental contamination according to the present invention ismanufactured by using a composition including only substances completelydegradable under environmental conditions. Disposable tableware preparedusing this composition is completely degraded under naturalenvironmental conditions and is suitable for compost.

The raw material composition of the disposable tableware according tothe present invention comprises crop residues, including straws of graincrops (e.g., rice, wheat and barley) and grain hulls such as chaff(including bran), corn flour (starch such as corn starch), papermulberry bark (a raw material of Korean traditional paper), a moss, anda grain flour mixture (a mixture of rice flour, barley flour (wheatflour), potato starch, glutinous rice flour and food powder).

Disposable tableware is manufactured by mixing the above separatelypulverized components in a proper ratio and compression-molding themixture in a metal mold at high temperature under high pressure using apress.

The composition used for manufacturing the disposable tableware of thepresent invention comprises 1–30 wt % of crop residues, including strawsof grain crops (e.g., rice, wheat and barley) and grain hulls such aschaff (including bran), 1–30 wt % of corn flour (starch such as cornstarch), 1–10 wt % of paper mulberry bark (a raw material of Koreantraditional paper), 1–10 wt % of a moss, and 30–96 wt % of a grain flourmixture. The grain flour mixture includes 10–15 wt % of barley flour(wheat flour), 1–20 wt % of potato starch, 5–13 wt % of glutinous riceflour, 5–12 wt % of rice flour and 60 wt % or higher of food powder asthe remaining part.

The components and their contents in the composition are determinedbased on the following factors.

The crop residues, including straws of grain crops (e.g., rice, wheatand barley) and grain hulls such as chaff (including bran), function tobind together components of disposable tableware to provide a desiredframe (shape). If the content of the crop residues is lower than 1 wt %,disposable tableware has a low binding strength so that it is difficultto maintain a desired shape. If the content of the crop residues ishigher than 30 wt %, disposable tableware is difficult to be molded in adesired shape.

The corn flour serves as a binder to increase the binding strength ofother components except for the corn flour. That is, the corn flourprevents tableware from being distorted and becoming misshaped, therebymaintaining binding strength and shape of other components. If thecontent of the corn flour is lower than 1 wt %, disposable tableware hasa low binding strength. If the content of the corn flour exceeds 30 wt%, tableware is very firm but is easily cracked.

The paper mulberry bark is used to increase the flexibility of tablewareand make the tableware durable. If the content of the paper mulberrybark is lower than 1 wt %, tableware is inflexibility. In contrast, theuse of the paper mulberry bark in an amount of higher than 10 wt %results in an undesired durability and firmness.

The moss is used to improve the antibacterial function of tableware. Ifthe moss is used in an amount of lower than 1 wt %, the tableware has areduced bactericidal activity. If the content of the moss exceeds 10 wt%, the tableware has a low binding strength.

Moss has been used for a very long period of time due to its highbactericidal activity. For example, according to a medical bible ofChinese Herbs and greatly advanced Chinese herbal medicine, called “BenCao Gang Mu”, which was created by the greatest Chinese herbal doctor LiShi Zhe during the Ming Dynasty of China, moss has the effects ofrelieving malaria, dyspepsia and bronchitis with fever and counteractingpoison. In addition, a number of information about the antimicrobialactivity of moss is available on the Internet.

The flexibility and firmness of the disposable tableware of the presentinvention are determined according to the ratio of the paper mulberrybark to the corn flour.

The grain flour mixture comprises the remaining part of the compositionof the present invention, which is composed of rice flour, barley flour,potato starch, and glutinous rice flour and food powder. The grain flourmixture is used for airtightness and waterproofing, and its ingredientsare used in a mixed form.

The rice flour has waterproofing, airtightness and coating functions.

The barley flour acts to weaken the high firmness of the potato starch.

The potato starch serves to reinforce binding strength and structuralstrength of tableware.

The glutinous rice flour functions to reinforce the coating to improvewater- and moisture-proofing functions.

The food powder, which accounts for most of the grain flour mixture, haswaterproofing, tightness and coating functions.

In addition, the barley flour content is determined based on thefollowing factors. If the barley flour content is lower than 10 wt %,the firmness of the potato starch is increased. If the barley flourcontent exceeds 15 wt %, the firmness of the potato starch is reduced.

The potato starch content is determined based on the following factors.If the potato starch content is lower than 1 wt %, tableware has a lowfirmness. If the potato starch content exceeds 20 wt %, tableware has ahigh firmness.

The content of the glutinous rice flour is determined based on thefollowing factors. If the glutinous rice flour is used in an amount oflower than 5 wt %, tableware has problems in coating, waterproofing andmoisture-proofing capacity. If the glutinous rice flour is used anamount of higher than 13 wt %, it reacts with the starch, resulting inincreased firmness of tableware, leading to formation of cracks in thetableware.

The rice flour content is determined by the following factors. If therice flour content is lower than 5 wt %, tableware has problems incoating, waterproofing and moisture-proofing capacity. If the rice flouris used an amount of higher than 12 wt %, it reacts with the starch,resulting in increased firmness of tableware, leading to formation ofcracks in the tableware.

The content of the food powder comprising the remaining part of thegrain flour mixture is the highest in the composition. The food powdershould account for at least 60% of the composition to maintain thewaterproofing, airtightness and coating functions of other components.

Hereinafter, a method of manufacturing disposable tableware bycompression molding using a press will be described in detail.

The disposable tableware is manufactured by determining the suitableamount of the components of the composition within ranges of 1–30 wt %for the crop residues, including straws of grain crops (e.g., rice,wheat and barley) and grain hulls such as chaff (including bran), 1–30wt % for the corn flour (starch such as corn starch), 1–10 wt % for thepaper mulberry bark (a raw material of Korean traditional paper), 1–10wt % for the moss, and 30–96 wt % for the grain flour mixture(particularly, 10–15 wt % for the barley flour, 1–20 wt % for the potatostarch, 5–13 wt % for the glutinous rice flour, 5–12 wt % for the riceflour and 60 wt % or higher for the food powder); finely pulverizingeach of the components; mixing the pulverized components; andcompression-molding the resulting mixture using a press to providedisposable tableware. This process for manufacturing disposabletableware will be described in more detail, as follows.

The components are supplied to a blender from a main material hopper,mixed in the blender and supplied as a feeder to a metal mold preheatedto 140–150° C. and connected to a 500-ton hydraulic press.

Several molded products may be simultaneously generated according to theintended use.

Each of the components is supplied to the main material hopper using amain material supplier (cartridge).

The range of the molding temperature is determined by the followingfactors. If the temperature is lower than the range, the components arenot molded. If the temperature is higher than the range, molded productsare baked.

The compression molding under the above press is carried out for aboutone minute.

When the mixture of the finely pulverized components is pressed in themetal mold at 140–150° C. using a 500-ton press, it is molded intodisposable tableware having open upper parts.

The disposable tableware is removed from the metal mold and transferredto a conveyor by a take-out robot.

Then, disposable tableware under transport on the conveyor are raised upand transferred to a pallet by a lifter. Molding defects (bugs) are thenremoved using a sandpaper of a trimming unit.

The trimmed tableware is finished with air in an air blowing unit, anddust is removed from the tableware.

The resulting tableware is subjected to a sterilization process.

The sterilized tableware is lifted, unloaded and packaged for sale.

A better understanding of the present invention may be obtained throughthe following example which is set forth to illustrate, but is not to beconstrued as the limit of the present invention.

EXAMPLE

From one metal mold, 81 paper coffee cups of the conventional size areproduced at once, and in case of relatively large tableware such asStyrofoam instant noodle cups, 12 to 16 products are obtained at once.Thus, one hundred million of coffee cups and thirty million of instantnoodle cups are produced every year.

The property of tableware is determined according to the ratio of rawmaterials. 30 wt % of bran, 30 wt % of corn flour, 5 wt % of papermulberry bark, 5 wt % of a moss, and 30 wt % of the grain flour mixture(15 wt % of barley flour, 15 wt % of potato starch, 5 wt % of glutinousrice flour, 5 wt % of rice flour and 60 wt % of food powder), based onthe total weight of the composition, 100 kg, were supplied from amaterial hopper to a blender, mixed in the blender and supplied as afeeder to a metal mold preheated to 140° C. Then, the mixture wascompression-molded using a 500-ton hydraulic press for one minute toproduce disposable tableware. The disposable tableware was very firm,had the color of bran, and was completely degraded within three to fourmonths under environmental (outdoor) conditions. When the content of thegrain flour mixture (powder) was increased, resulting tableware wasfirmer and durable and useable as a water container for a long period oftime, and required one year or longer for complete degradation underenvironmental conditions.

When the content of the paper mulberry bark was increased, the resultingtableware had reduced firmness, but was flexible and maintained adesired breakage resistance so that the tableware was not easily broken.

Thus, if this tableware is used indoors without exposure to outdoorconditions and is preserved in a moisture-free state after being used,this tableware is believed to be multi-purpose green tableware that canbe used semi-permanently.

The tableware was not damaged even when falling from the average heightof desks for standing work, 1 m 50 cm. Also, the tableware is notharmful to humans because its main components are derived from materialsdirectly associated with foods.

Although the preferred embodiment of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

INDUSTRIAL APPLICABILITY

As described hereinbefore, the present invention has advantages in thatthe straws and corn flour have binding ability, elasticity andsolubility, which are responsible for maintaining the shape oftableware, and thus have high affinity to starch used as another rawmaterial in tableware preparation and serve to increase the bindingstrength of the starch. The advantages of the present invention furtherinclude that the paper mulberry bark offers tableware elasticity toallow the tableware not to be broken by a certain degree of impact, andthat the moss improves the freshness of the contents of the tablewaredue to its antibacterial activity. The advantages yet further includethat tableware is waterproof due to the grain flour mixture withoutrequiring additional waterproofing coating.

When buried under the ground, disposable tableware according to thepresent invention is completely degraded by water or moisture with thepassage of time. Such degradation products can be used as compost. Also,the disposable tableware of the present invention is advantageous interms of being capable of being used as livestock feed even when theyare discarded along with food waste without separation in restaurants.Further, when discarded in mountains or resorts, the present disposabletableware is dissolved and buried under the ground with the passage oftime while not harming nature and the environment. Therefore, thepresent invention is useful in related industrial fields.

1. Disposable tableware completely degradable under environmentalconditions without environmental contamination, which is prepared byfinely pulverizing and mixing 1–30 wt % of crop residues, 1–30 wt % ofcorn flour, 1–10 wt % of paper mulberry bark, 1–10 wt % of a moss and30–96 wt % of a grain flour mixture, and compression-molding a resultingmixture to a predetermined shape and size at high temperature under highpressure.
 2. The disposable tableware completely degradable underenvironmental conditions without environmental contamination accordingto claim 1, wherein the crop residues are selected from straws of rice,wheat, barley and other grain crops, chaff, bran, and mixtures thereof.3. The disposable tableware completely degradable under environmentalconditions without environmental contamination according to claim 1,wherein the grain flour mixture comprises 10–15 wt % of barley flour,1–20 wt % of potato starch, 5–13 wt % of glutinous rice flour, 5–12 wt %of rice flour and 60 wt % or higher of food powder as the remainingpart.
 4. A method of manufacturing disposable tableware completelydegradable under environmental conditions without environmentalcontamination using plants and crops as main materials, comprising:determining a composition for preparing the disposable tableware, whichincludes 1–30 wt % of crop residues, 1–30 wt % of corn flour, 1–10 wt %of paper mulberry bark, 1–10 wt % of a moss, and, as a remaining part, agrain flour mixture wherein, the grain flour mixture includes 10–15 wt %of barley flour, 1–20 wt % of potato starch, 5–13 wt % of glutinous riceflour, 5–12 wt % of rice flour and, as a remaining part, 60 wt % orhigher of food powder, finely pulverizing each component, and mixingpulverized components; and compression-molding a resulting mixture in ametal mold preheated to 140–150° C. and connected to a 500-ton hydraulicpress to provide disposable tableware.
 5. The method of manufacturingdisposable tableware completely degradable under environmentalconditions without environmental contamination according to claim 4,wherein the crop residues are selected from straws of rice, wheat,barley and other grain crops, chaff, bran, and mixtures thereof.